Comparison of B-cell Depletion by Rituximab and Anti-CD 19 CAR-T Therapy in Patients With Rheumatoid Arthritis

The goal of this phase I/II clinical trial is to compare B-cell depletion by rituximab and anti-CD 19 CAR-T therapy in patients with rheumatoid arthritis. The main questions it aims to answer are: * To assess the safety of anti-CD19 CAR T cell therapy in subjects with active, ACPA positive and treatment refractory RA (Phase-I) * To assess the safety of anti-CD19 CAR T cell therapy and of rituximab in subjects with active, ACPA positive and treatment refractory RA (Phase-II) * To assess ACPA seroconversion after anti-CD19 CAR T cell or rituximab therapy in subjects with active, ACPA positive and treatment refractory RA (Phase-II) Participants in the test-arm will receive a single dose of KYV-101 i.v., an autologous fully-human anti-CD19 CAR T-cell immunotherapy. In the comparator group patients will receive 2x1 g Rituximab i.v. Follow-up time (both arms) is 52 weeks with regular visits at the site.